Ultrasonic transducer and signal decay time adjusting method applied thereto

Abstract

A signal decay time adjusting method is used in an ultrasonic transducer. Firstly, a first driving signal is generated by a pre-processing module. When the first driving signal is received, an ultrasonic transmitting/receiving module generates vibration and transmits a sensing wave according to the first driving signal. Then, the pre-processing module stops generating the first driving signal so that the vibration generated within the ultrasonic transmitting/receiving module is decayed as a decay signal. Then, a second driving signal is generated by the pre-processing module according to the first driving signal, and the second driving signal is transmitted to the ultrasonic transmitting/receiving module. When the second driving signal is received, the decay signal is offset according to the second driving signal, so that a decay time of the decay signal is shortened. When the sensing wave is reflected by an object, a reflective wave is received by the ultrasonic transmitting/receiving module.

1 . A signal decay time adjusting method for an ultrasonic transducer, the ultrasonic transducer comprising a pre-processing module and an ultrasonic transmitting/receiving module, the signal decay time adjusting method comprising steps of:
 generating a first driving signal by the pre-processing module;   generating vibration and transmitting a sensing wave by the ultrasonic transmitting/receiving module according to the first driving signal when the first driving signal is received;   stopping generating the first driving signal so that the vibration generated within the ultrasonic transmitting/receiving module is decayed as a decay signal;   generating a second driving signal by the pre-processing module according to the first driving signal, and transmitting the second driving signal to the ultrasonic transmitting/receiving module;   offsetting the decay signal according to the second driving signal when the second driving signal is received by the ultrasonic transmitting/receiving module so that a decay time of the decay signal is shortened; and   receiving a reflective wave when the sensing wave is reflected by an object.   
     
     
         2 . The signal decay time adjusting method according to  claim 1 , further comprising a step of determining a distance between the ultrasonic transducer and the object according to a time interval from generation of the sensing wave and receipt of the reflective wave. 
     
     
         3 . The signal decay time adjusting method according to  claim 1  wherein the first driving signal has a first phase, a first amplitude, a first pulse number and a first frequency, and the second driving signal has a second phase, a second amplitude, a second pulse number and a second frequency. 
     
     
         4 . The signal decay time adjusting method according to  claim 3 , further comprising a step of setting the second amplitude to be equal to the first amplitude. 
     
     
         5 . The signal decay time adjusting method according to  claim 3  wherein the second frequency is equal to the first frequency, and there is a phase shift between the second phase and the first phase. 
     
     
         6 . The signal decay time adjusting method according to  claim 5 , further comprising a step of setting the phase shift such that the second driving signal and the first driving signal have different phases or they are out of phase. 
     
     
         7 . The signal decay time adjusting method according to  claim 3  wherein the second frequency and the first frequency are different. 
     
     
         8 . The signal decay time adjusting method according to  claim 3 , further comprising a step of setting the second pulse number. 
     
     
         9 . An ultrasonic transducer having a function of adjusting a signal decay time, the ultrasonic transducer comprising:
 a pre-processing module for generating a first driving signal, and generating a second driving signal according to the first driving signal after the first driving signal is stopped; and   an ultrasonic transmitting/receiving module in communication with the pre-processing module for receiving the first driving signal, and generating vibration and transmitting a sensing wave according to the first driving signal, wherein the second driving signal is received by the ultrasonic transmitting/receiving module after the pre-processing module stops generating the first driving signal, the vibration generated within the ultrasonic transmitting/receiving module is decayed as a decay signal, and the decay signal is offset according to the second driving signal so that a decay time of the decay signal is shortened.   
     
     
         10 . The ultrasonic transducer according to  claim 9  wherein the first driving signal has a first phase, a first amplitude, a first pulse number and a first frequency, and the second driving signal has a second phase, a second amplitude, a second pulse number and a second frequency. 
     
     
         11 . The ultrasonic transducer according to  claim 10  wherein the second amplitude is set to be equal to the first amplitude. 
     
     
         12 . The ultrasonic transducer according to  claim 10  wherein the second frequency is equal to the first frequency, and there is a phase shift between the second phase and the first phase. 
     
     
         13 . The ultrasonic transducer according to  claim 12  wherein the phase shift is set such that the second driving signal and the first driving signal have different phases or they are out of phase. 
     
     
         14 . The ultrasonic transducer according to  claim 10  wherein the second frequency and the first frequency are different. 
     
     
         15 . The ultrasonic transducer according to  claim 10  wherein the second pulse number is preset. 
     
     
         16 . The ultrasonic transducer according to  claim 10 , further comprising:
 a microprocessor for processing the first phase and the second phase;   a signal amplitude modulator disposed within the microprocessor for adjusting the first amplitude and the second amplitude; and   a driving circuit disposed within the pre-processing module and in communication with the signal amplitude modulator for outputting the first driving signal and the second driving signal.   
     
     
         17 . The ultrasonic transducer according to  claim 16  wherein the first frequency, the first pulse number, the second frequency and the second pulse number are set by the microprocessor. 
     
     
         18 . The ultrasonic transducer according to  claim 16  wherein the ultrasonic transmitting/receiving module comprises:
 a transmitter in communication with the driving circuit for receiving the first driving signal, and generating the vibration and transmitting the sensing wave according to the first driving signal; and 
 a receiver for receiving the reflective wave. 
 
     
     
         19 . The ultrasonic transducer according to  claim 18 , further comprising a receiving circuit, which is disposed within the pre-processing module and in communication with the receiver, wherein a distance between the ultrasonic transducer and the object is determined according to a time interval from generation of the sensing wave and receipt of the reflective wave.